Biggest Accelerator

For ten months the world's most powerful particle accelerator (or atom smasher) was at Geneva, Switzerland, generating a beam of protons with up to 28 Bev (billion electron-volts) of energy. Last week the energy championship came back to the U.S. At Brookhaven National Lab oratory, Long Island, the new alternating gradient synchroton, which scientists call AGS, was kicked up to full power for the first time, generating a proton beam that stayed steady at 30 Bev and hovered for short periods as high as 31 Bev, accelerating particles at rates only a fraction below the 186,300 miles-per-second speed of light. Eventually, Brookhaven expects to boost its power to about 33 Bev.

Half-Mile Tube. Five years under construction at a cost of $31 million, Brookhaven's AGS looks from outside like a circular ridge of earth half a mile in circumference. Under the ridge is a circle of electromagnets weighing 4,000 tons, and inside the magnets runs a ring-shaped metal tube 7 in. wide and 3 in. high, which is pumped free of air. Bursts of protons (nuclei of hydrogen atoms) are shot into the tube by a smaller accelerator, and the magnets guide them around its half-mile circuit. Entering with 50 Mev (million electron-volts) of energy, the protons are grabbed by quickly shifting electrical forces and accelerated to their fantastic speeds.

Each burst lasts only one second, but during the flight the protons circle the track 300,000 times and travel 150,000 miles. At the end of their trip they are moving at an infinitesimal fraction below the speed of light. Since Einstein's relativity requires that mass must increase with speed, the protons gain 30 times the mass that they have while at rest.

10 Billion Protons. The Brookhaven AGS delivered its powerful beam with remarkable ease. The scientists adjusted its complex machinery for only nine days before the injected particles reached 30 Bev. Another triumph for Brookhaven is that each pulse of the beam contains 10 billion protons. Some accelerators have pushed their particles to scheduled speed but delivered only a comparative few. The Soviet 10-Bev accelerator at Dubna is apparently plagued with this trouble. U.S. physicists, who would be quick to praise their Russian colleagues if praise were due, estimate that its pulses contain 10 million protons, one-thousandth of the number in a fat Brookhaven pulse.

The AGS will be used primarily to explore the intimate nature of matter--a problem that seems to grow more baffling as its outermost fringes are explored. Brookhaven's 30-Bev protons will be shot against other protons, eventually in an 80-in. liquid-hydrogen bubble chamber, the world's largest, which is now being designed. Out of the proton-proton collision will come a weird menagerie of short-lived particles. Many of them will be new to science, and they are almost certain to have properties that no one can imagine today. AGS will reach a long way into nature's mystery, but it may find many more puzzles than it solves.

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